High average power CW or pulsed carbon dioxide lasers, of the type useful in any meaningful materials processing application, have historically featured large volume discharges, cooled by massive forced convection. As a consequence, such lasers have invariably been characterized by a large physical size, incorporating a relatively complicated gas transport and heat-exchange system.
Due to the many and rapidly moving parts inherent in their design, these large machines have not only been costly to build and install, but in addition require considerable peripheral equipment, and frequent supervision to achieve proper operation. Because of these factors, they have proven to be unsuitable for a number of applications where mobility, weight, or freedom from service and operator intervention are prime considerations.
Thus, despite a number of impressive laser developments reported in the trade literature, it has become well recognized that to achieve widespread adoption of lasers for the processing of materials it will be necessary to develop more compact high powered laser systems, which are capable of prolonged operation in an industrial environment, without the need for frequent adjustment or maintenance.
The above is particularly true in robotic applications for flexible manufacturing, where portability is an additional constraint.
Being cognizant of this fact, a number of researchers have recently devoted considerable effort into the development of new laser geometries which conceivably could address this problem. In particular, research work on diffusion cooled R.F. excited lasers, of both wave-guide and strip-line or slab geometries, has demonstrated that useful power levels can be achieved from very small packages, without any form of gas transport.
Anticipated further advances in this particular art should raise the attainable power into the many hundreds of watt category, and perhaps even near the 1 kilowatt level. However, direct scaling of the approach into the MULTIKILOWATT range, as is desirable in many industrial situations, presents considerable difficulty.
Because of this fact, increasing attention is being focused on multiple beam systems, constructed with a number of identical waveguide discharge channels, optically coupled either individually or by a common resonator.
When the individual lasers in such a system operate independently their output radiation is non-phase coherent. Consequently, the diffraction limit and focusability of the resultant beam does not benefit from the increased aperture of the assembly. Fortunately, coherent phase-locking of the individual gain sections has been demonstrated to provide a viable solution to this important problem.
The approaches thus far developed have been appropriate to parallel waveguide or tubular discharge sections, but not to slab gain geometries. The object of this patent application is therefore to teach the construction of a multi-channel parallel-slot excitation and optical extraction geometry. The device has no moving parts and appears scalable well into the multikilowatt range, in a very small physical package. The basic technique is also applicable to a number of gas discharge excitation processes utilizing different energy sources.